DE102013106324A1 - Method and system for heating the traction battery of an electric vehicle - Google Patents

Abstract

An electric vehicle, such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a purely battery-operated electric vehicle (BEV), contains a traction motor. The battery discharges electrical current for the vehicle drive. In addition to a current component for the vehicle drive, the discharge current contains an alternating current (AC) component for heating the battery. The current component for the vehicle drive can be a direct current (DC) component.

Description

TECHNICAL AREA

The present invention relates to the heating of the traction battery of an electric vehicle.

BACKGROUND

An electric vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV) and a battery-powered electric vehicle (BEV) have one Electric motor and a traction battery on. The engine is disposed between the battery and a drive shaft of the vehicle, the engine being coupled to the driveline of the vehicle. The engine may be controlled to use energy from the battery to contribute positive wheel torque to the wheels of the vehicle to propel the vehicle.

Conversely, the engine may be controlled to contribute negative wheel torque to the vehicle braking wheels. During a process called regenerative braking, the kinetic energy stored in the braking vehicle is accumulated when the battery is charged during vehicle deceleration. During regenerative braking, required wheel braking torque is distributed between the friction brake and the engine acting as a generator to charge the battery.

The ability of a typical traction battery to accumulate regenerative braking energy is limited as the temperature of the battery decreases, which is particularly noticeable below freezing. In a method of heating the battery to overcome this reduction in collection capacity, energy is cycled into and out of the battery. At relatively low temperatures, however, relatively little energy can be returned to the battery. In this case, the discharge current provides all battery heating.

SUMMARY

An embodiment of the present invention provides a method that includes discharging electrical power from a traction battery of a vehicle drive vehicle. The discharge current contains an AC component (AC component) for heating the battery.

The discharge current may further include a DC component for the vehicle drive. The AC component causes the battery to generate more heat loss than heat loss alone from the DC component to thereby facilitate heating of the battery. In one embodiment, the AC component has a frequency between 0 Hz and 300 Hz.

The method may include generating a motor torque signal indicative of (i) engine torque to be generated for vehicle propulsion by a motor connected to the battery through the motor using the DC component of the discharge current and (ii) the AC component of the discharge current to heat the battery , by a control include. The method may include supplying the motor torque signal to the motor to operate the battery to discharge the discharge current.

The method may include supplying the discharge current from the battery to a motor connected to the battery. The method may include converting the discharge current through the motor into a mechanical torque and supplying the mechanical torque from the engine to a transmission to allow the transmission to use the mechanical torque to drive the vehicle.

The method may include reducing the AC component of the discharge current over time with heating of the battery such that the discharge current has substantially no AC component after the temperature of the battery has increased to a sufficient threshold.

An embodiment of the present invention provides a system having a controller configured to discharge electrical power from a traction battery for vehicle propulsion. The discharge current contains an AC component for heating the battery.

One embodiment of the present invention provides a vehicle having a transmission, an engine configured to provide engine torque to the transmission for propelling the vehicle, and a traction battery. The battery is configured to discharge electrical current to the motor for the motor to use to generate motor torque. The discharge current contains an AC component for heating the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

1 FIG. 12 illustrates a block diagram of an exemplary hybrid vehicle powertrain according to one embodiment of the present invention; FIG. and

2 provides a flowchart illustrating the operation of a method and system for Modifying the DC load of the traction battery to include an AC component for heating the battery, according to an embodiment of the present invention.

DETAILED DESCRIPTION

Detailed embodiments of the present invention are disclosed herein, but it should be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various and alternative forms. The figures are not necessarily to scale; Some features may be exaggerated or minimized to show details of particular embodiments. The specific structural and functional details disclosed herein are therefore not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

Now on 1 Referring to FIG. 1, a block diagram of an exemplary powertrain system will be described 10 for a hybrid electric vehicle (HEV) according to an embodiment of the present invention. The powertrain system 10 contains an engine 20 , an electric machine, such as an electric motor / generator 30 ("Engine"), an automatic multi-speed transmission 50 and a friction braking system.

The engine 20 has an output shaft 22 on that by an engine clutch 32 (ie a disconnect clutch 32 ) with an input shaft 24 of the motor 30 connectable and separable from it. The motor 30 has an output shaft 42 on that by a motor clutch 52 (ie a starting clutch 52 ) with an input shaft 44 of the transmission 50 connectable and separable from it. Although the couplings 32 and 52 As hydraulic couplings are described and illustrated, other types of couplings, such as electromechanical couplings, may be used.

The gear 50 contains several gear ratios and is equipped with a drive shaft 54 (That is, an output shaft of the transmission 50 ) connected. The output shaft 54 is with a differential 56 connected. A left and a right drive wheel 60 . 62 are by a left and a right axis 64 . 66 with the differential 56 connected. In this arrangement, transmits the transmission 50 a driveline output torque 68 on the drive wheels 60 . 62 , The wheels 60 . 62 are with friction brakes 70 for applying a braking force for the purpose of slowing down the vehicle.

The starter motor 34 is through the wiring 38 with a traction battery 36 It is also used as a generator to generate electrical energy for storage in the battery 36 can be used. In operation, the engine can 20 the starter motor 34 Feed in energy so that the starter motor 34 electrical energy for storage in the battery 36 generated. The motor 30 is through the wiring 53 also with the battery 36 connected.

The engine 20 is a primary energy source for the powertrain system 10 , and the battery 36 is a secondary energy source for the powertrain system 10 , The engine 20 is an internal combustion engine, such as an engine driven by gasoline, diesel or natural gas. The engine 20 generates a first input torque 76 (that is, an engine torque) that is the engine 30 is fed when the engine 20 and the engine 30 over the engine clutch 32 are connected. To drive the vehicle with the engine 20 will be at least part of the first input torque 76 from the engine 20 through the engine clutch 32 to the engine 30 and then from the engine 30 through the engine clutch 52 to the gearbox 50 transfer. The engine 20 leads the engine 30 also energy through the engine clutch 32 too, so the engine 30 act as a generator and electrical energy for storage in the battery 36 can generate.

Depending on the particular operating mode of the vehicle, the engine is transmitting 30 either the battery 36 Energy or convert in the battery 36 stored electrical energy in a second input torque 78 (that is, in a motor torque). The second input torque 78 is through the engine clutch 52 also to the transmission 50 Posted. When generating electrical energy for storage in the battery 36 contains the engine 30 Energy either from the engine 20 in a driving mode or inertia in the vehicle when the engine is running 30 acts as a brake in a so-called regenerative braking mode.

As described, the engine 20 , the engine clutch 32 , the motor 30 , the engine clutch 52 and the gearbox 50 sequentially connectable in series, as in 1 shown. Thus, the powertrain system provides 10 a parallel or modular hybrid transmission ("MHT") configuration (MHT - modular hybrid transmission) in which the engine 20 through the engine clutch 32 with the engine 30 connected, the engine 30 through the engine clutch 52 with the transmission input shaft 44 connected is.

Depending on whether the engine clutch 32 and the engine clutch 52 are engaged or disengaged, it is determined which input torques 76 and 78 to the gearbox 50 be transmitted. If the engine clutch 32 is disengaged, then, for example, only the second input torque 78 from the engine 30 the transmission 50 fed. If both clutches 30 . 52 are engaged, then both the first and the second input torque 76 . 78 from the engine 20 or from the engine 30 the transmission 50 fed. If only from the engine 20 Input torque for the gearbox 50 is desired, of course, both clutches 32 and 52 engaged, but the engine 30 is not energized, so the first input torque 76 from the engine 20 only the gearbox 50 is supplied. The driveline output torque 68 corresponds to the sum of the gear 50 supplied engine torque 76 and engine torque 78 ,

The gear 50 includes a plurality (not shown) planetary gear sets, which are selectively placed by selectively engaging a plurality of friction elements in different gear ratios to produce the desired multiple gear ratios. For example, the friction elements of the transmission 50 by a load-accepting friction element 72 (ie, an on-coming clutch ("OCC")), a load-releasing friction element 73 (ie, an off-going clutch ("OGC")) and a forward clutch 74 be formed. The friction elements of the gearbox 50 are controllable by a circuit diagram that includes specific elements of the planetary gear sets of the transmission 50 connects and disconnects to control the relationship between the transmission output and the transmission input.

The gear 50 is automatically switched from one ratio to another based on the requirements of the vehicle. Then the gearbox leads 50 the driveline output torque 68 the output shaft 54 to. The driveline output torque 68 ultimately drives the drive wheels 60 . 62 at. The kinetic details of the transmission 50 can be formed by a wide range of gear arrangements. The gear 50 is an example of a transmission assembly for use with embodiments of the present invention. Any multi-speed transmission that receives one or more input torques from an engine and / or engine and then provides torque to an output shaft in various gear ratios is acceptable for use with embodiments of the present invention. These include automatic and manual transmissions. Stepless, dual clutch, and infinitely variable transmissions are acceptable for use with embodiments of the present invention.

Furthermore, contains the powertrain system 10 a powertrain control unit 80 and a brake control unit 85 , The control units 80 and 85 together form a vehicle system control. Based on the repositioning of a brake pedal 92 the driver of the vehicle provides a total braking torque request signal 94 if the driver wants to slow down the vehicle. The stronger the driver on the pedal 92 presses, the more wheel brake torque is required. The brake control unit 85 divides the total wheel brake torque between a powertrain braking torque signal 95 (representing the torque level to be obtained by regenerative braking) and a friction braking torque signal 96 (the one through the friction brakes 70 to be maintained torque level represents) on.

The brake control unit 85 provides the friction brake torque signal 96 to the friction brakes 70 for the friction brakes to apply the friction braking torque to the drive wheels. The brake control unit 85 provides the driveline brake torque signal 95 to the powertrain control unit 80 , In response, the powertrain control unit sends 80 a motor torque signal 98 to the engine 30 that represents the required engine torque height to be provided by regenerative braking. The motor 30 in turn generates the Nutzbremsdrehmoment and thereby leads to the transmission 50 a negative input torque.

The powertrain control unit 80 receives torque ratio signals 101 from the gearbox 50 in terms of shifting from one gear ratio to another, such as during a gear shift. The powertrain control unit 80 Also receives a powertrain torque signal 99 , which has a total driveline output torque level 68 represents.

To drive the vehicle transmits the powertrain control unit 80 an engine torque signal 100 to the engine 20 , which indicates how much engine torque is required at a given time. In response, the engine becomes 20 operated to engine torque 76 according to the engine torque signal 100 to create. Similarly, the powertrain control unit sends 80 a motor torque signal 98 to the engine 30 , which indicates how much motor torque is required at a given time. In response, the engine becomes 30 operated to motor torque 78 according to the engine torque signal 98 to create. The Powertrain output torque 68 corresponds to the sum of the gear 50 supplied engine torque 76 and engine torque 78 , If both clutches 32 . 52 are engaged, both the engine torque 76 as well as the engine torque 78 the transmission 50 fed. In this case, the powertrain output torque corresponds 68 the sum of the engine torque 76 and the engine torque 78 ,

The motor 30 contains one from the battery 36 discharged electric current to the motor torque 78 to create. The discharge current for generating the engine torque 78 is a direct current (DC) load of the battery 36 , The motor 30 converts the discharge current into a mechanical torque (that is, the engine torque 78 ) around.

The amount of discharge current from the battery 36 corresponds to the height of the engine torque to be generated 78 , Of course, the discharge current from the battery 36 at a fixed voltage of the battery 36 proportional to engine power (ie, V · I = power) and engine power is the product of engine torque 78 and the speed of the engine 30 , As mentioned above, the amount of motor torque to be generated is based 78 on the engine torque signal 98 from the powertrain control unit 80 , Thus, the powertrain control unit 80 the engine 30 for generating various engine torques 78 by receiving correspondingly different discharge currents from the battery 36 Taxes. The powertrain control unit 80 controls the engine 30 for generating various engine torques 78 by controlling according to different engine torque signals 98 to the engine 30 ,

The fortune of the battery 36 Collecting regenerative braking energy occurs when the temperature of the battery drops 36 limited to freezing. Control strategies according to embodiments of the present invention add to the discharge current load of the battery 36 an alternating current (AC) component to the battery 36 to warm up. That is, these control strategies modify the discharging current load of the battery 36 to an AC component to heat the battery 36 to include. For example, the cells of the battery 36 heated. In one embodiment, the powertrain control unit adds 80 the motor torque signal 98 an AC fault to the discharge current load of the battery 36 to add the AC component. That is, in this embodiment, the electric drive torque driver is modified to accommodate the AC noise. In one embodiment, the AC component is a low frequency AC component on the order of 0 Hz to 300 Hz.

As an example of adding an AC component to the discharge current of the battery 36 will take a DC current drain of ten amps from the battery 36 considered. When a peak-to-peak AC current draw of ten amps is added to the DC current, the battery experiences 36 no charge current. However, in this example, the average current drain remains at 10 amps with a 12% increase in the I2R loss of the battery.

Now on 2 Referring to Figure 1, a flow chart will be given 200 demonstrated the operation of a method and system for modifying the DC load of the battery 36 so that they have an AC component to warm up the battery 36 contains, according to an embodiment of the present invention describes. It comes to the expiration, when the vehicle with a powertrain output torque 68 based on at least one engine torque 78 is driven. The engine torque 76 can the gearbox 50 be supplied to the drive of the vehicle during the process or not supplied.

The process begins with the powertrain control unit 80 a motor torque signal 98 generated to the engine 30 to control, a corresponding engine torque 78 to generate the drive of the vehicle. In particular, the powertrain control unit generates 80 the motor torque signal 98 with an added AC component fault. Thus, the engine torque signal is included 98 a DC power load indicating component and an AC power load indicating component. The DC component corresponds to the motor torque to be generated for the vehicle drive 78 , The AC component corresponds to the added AC fault for battery warming. Without the added AC component disturbance, the motor torque signal would 98 be a typical motor torque signal indicating the DC current load throughout. The engine torque signal 98 for the vehicle drive with the added AC fault for the battery heating becomes the engine 30 directed, as in block 202 shown.

In response to the engine torque signal 98 from the powertrain control unit 80 to the engine 30 the battery discharges 36 electric current to the engine 30 as in block 204 shown. The discharge current contains the DC component, which is the motor torque to be generated for the vehicle drive 78 corresponds to, and the AC component, that for the heating of the battery 36 added AC interference corresponds.

The motor 30 generates the engine torque 78 according to the driven motor torque signal 98 as in block 206 shown. The motor 30 leads the engine torque 78 over the engaged engine clutch 52 the transmission 50 to the driveline output torque 68 to generate for the drive of the vehicle, as in block 208 shown.

The AC component may involve heating the battery 36 be reduced over time, so that the discharge current does not contain any AC component or substantially no AC component when the temperature of the battery 36 has increased to a sufficient threshold. Conversely, the AC component may be increased over time to account for the fact that the battery is leaking 36 has not heated within a sufficient amount of time.

As mentioned, the powertrain output torque is 68 the sum of the engine torque 76 and the engine torque 78 when both torques 76 . 78 the transmission 50 be supplied. If necessary, the powertrain control unit 80 accordingly the engine 20 corresponding to the engine torque signal 98 control the added AC disturbance to account for any effects on motor torque caused by the AC disturbance 78 repealed. This option is available because the powertrain output torque 68 the sum of the engine torque 76 and the engine torque 78 equals if both torques 76 . 78 the transmission 50 be supplied.

In another embodiment, the engine 30 as a generator for the battery 36 operated. In this embodiment, the engine provides 20 Power through the engine clutch 32 to the engine 30 so the engine 30 can act as a generator and electrical energy for storage in the battery 36 can generate. In this embodiment, the output electric power of the engine 30 to battery 36 varies to add the AC noise for the battery heating of the delivered electrical energy. In this case, the typical emitted electrical energy of the engine 30 for the battery 36 modified with the added AC noise.

Embodiments of the present invention are applicable to lithium-ion batteries. Embodiments of the present invention take advantage of the characteristics that at low AC frequencies (for example, between 0 Hz to 300 Hz), the temperature of a lithium-ion battery can be increased significantly faster than simply discharging the battery with a DC power load, or with im Ratio of higher AC frequencies. The battery can be increased significantly faster at these low AC frequencies because the battery has its highest resistance at these low AC frequencies. Accordingly, adding an AC component having frequencies between 0 Hz and 300 Hz may result in the DC current drain from the battery 36 effectively reduce the time it takes for the battery to warm up. As a result, the fortune of the battery 36 To absorb regenerative braking energy increases. As described herein, the addition of this frequency component (or frequency components) to the DC current drain from the battery 36 by adding a disturbance to the current control for the drive system.

With low frequency interference added to the drive system, the time until the battery reaches a temperature that allows for the absorption of regenerative braking energy can be reduced while providing full functionality of the vehicle to the vehicle operator. This reduced time may provide improved low temperature regenerative braking, resulting in increased vehicle operating range. As described, the method of adding the low frequency or low frequency component to the DC current drain from the battery 36 by adding a disturbance to the current control for the drive system. As known to those of ordinary skill in the art, this can be accomplished in a variety of ways. An example will be in IEEE Vehicle Power and Propulsion Conference (VPPC), 3-5 September, 2008, Harbin, China 978-1-4244-1849-7 / 08 2008 . IEEE Design & Implementation of a Novel Vector-Controlled Drive by Direct Injection of Random Signal, A. Zabihinejad and JS Moghani , described.

As described herein, the powertrain system is 10 an example of a powertrain system for use with embodiments of the present invention. The powertrain system 10 FIG. 12 illustrates a parallel hybrid electric vehicle configuration. Other hybrid electric vehicle powertrains with embodiments of the present invention may be used. Likewise, plug-in hybrid electric vehicle powertrains and all-battery electric vehicle powertrains with embodiments of the present invention may be used. In general, any electric vehicle having a motor disposed between a traction battery and a transmission may be used with embodiments of the present invention. Such electric vehicles may optionally include an engine.

Although embodiments are described above, these embodiments are not intended to describe all possible forms of the invention. Instead, the terms used in the description are descriptive and not limiting terms, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Moreover, the features of various implementation embodiments may be combined to form further embodiments of the present invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• IEEE Vehicle Power and Propulsion Conference (VPPC), 3-5 September, 2008, Harbin, China 978-1-4244-1849-7 / 08 2008 [0041]
• IEEE Design & Implementation of a Novel Vector-Controlled Drive by Direct Injection of Random Signal, A.Zabihinejad and JS Moghani [0041]

Claims (20)

A method comprising: Discharging electric power from a traction battery of a vehicle for vehicle propulsion, the discharging current comprising, in addition to a current component for vehicle propulsion, an AC component for heating the battery. The method of claim 1, wherein: the power component for the vehicle drive is a direct current (DC) component. The method of claim 2, wherein: the AC component causes the battery to generate more heat loss than heat loss alone from the DC component, thereby facilitating heating of the battery. The method of claim 1, wherein: the AC component has a frequency of between 0 Hz and 300 Hz. The method of claim 2, further comprising: Generating an engine torque signal indicated by (i) an engine torque to be generated for vehicle propulsion by a motor connected to the battery through the motor using the DC component of the discharge current and (ii) the AC component of the discharge current to heat the battery. The method of claim 5, further comprising: Supplying the motor torque signal to the motor to operate the battery to discharge the discharge current. The method of claim 2, further comprising: Supplying the discharge current from the battery to a motor connected to the battery. The method of claim 7, further comprising: Converting the discharge current through the motor into a mechanical torque; and Supplying the mechanical torque from the engine to a transmission so that the transmission can use the mechanical torque to drive the vehicle. The method of claim 1, further comprising: Reducing the AC component of the discharge current over time with heating of the battery, so that the discharge current has at least substantially no AC component after the temperature of the battery has increased to a sufficient threshold. A system comprising: a controller configured to discharge electric power from a traction battery for vehicle propulsion, wherein the discharge current includes, in addition to a current component for vehicle propulsion, an AC component for heating the battery. The system of claim 10, wherein: the power component for the vehicle drive is a direct current (DC) component. The system of claim 10, wherein: the AC component has a frequency of between 0 Hz and 300 Hz. The system of claim 11, further comprising: that the controller is configured to generate a motor torque signal indicated by (i) motor torque to be generated for vehicle propulsion by a motor connected to the battery through the motor using the DC component of the discharge current; and (ii) the AC component of the motor Discharge current for heating the battery; in that the controller is further configured to supply the motor torque signal to the motor for operating the battery to discharge the discharge current. The system of claim 10, wherein: the controller is further configured to reduce the AC component of the discharge current over time with heating of the battery such that the discharge current has substantially no AC component after the temperature of the battery has increased to a sufficient threshold. A vehicle comprising: a gearbox; a motor configured to provide engine torque to the transmission for propelling the vehicle; and a traction battery configured to discharge electrical power to the engine for use by the engine to generate motor torque, the discharge current including, in addition to a current component for vehicle propulsion, an AC component for heating the battery. The vehicle of claim 15, wherein: the power component for the vehicle drive is a direct current (DC) component. A vehicle according to claim 15, wherein: the AC component has a frequency of between 0 Hz and 300 Hz. The vehicle of claim 16, further comprising: a controller configured to generate a motor torque signal indicated by (i) a motor torque to be generated for vehicle propulsion by a motor connected to the battery through the motor using the DC component of the discharge current and (ii) the AC component the discharge current for heating the battery. The vehicle of claim 18, wherein: the controller is further configured to supply the motor torque signal to the motor to operate the battery to discharge the discharge current. A vehicle according to claim 15, wherein: the vehicle is a hybrid electric vehicle, a plug-in hybrid electric vehicle or a purely battery-powered electric vehicle.

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